1. Field of the Invention
The present invention relates generally to secondary battery cells, and more specifically to systems and methods for charging secondary battery cells.
2. Description of the Related Art
Generally, image capture systems, typified by digital cameras and video cameras, derive power from removable secondary cells.
Conventional systems for charging such secondary cells are well known. In one method, the secondary cell is charged separately from the image capture system. That is, the secondary cell is removed from the image capture system and attached to a separate charger to charge the secondary cell. In another method, the secondary cell is charged without removal from the image capture system. Here, the charging circuit and the image capture system are integrated so that the secondary cell can be charged within the image capture system.
Accordingly, the secondary cell to be charged and the charger/charging circuit should be compatible particularly when the secondary cell and the charger are integrated. That is, the charger/charging circuits are designed to use a valid battery (includes secondary cell and a computer) type. Charging a secondary cell different from a valid battery type can result in malfunction of the charger/charging circuit or a decrease in life of the secondary cell. This is indicated in, for example, Japanese Patent Laid-Open No. 8-182206. Another related art system is disclosed in Japanese Patent Laid-Open No. 2001-135360.
In particular, if the charging circuit malfunctions, the user must leave the image capture system (e.g., digital camera or video camera), in a service center for repair. Hence, the user is deprived of beneficial use and enjoyment of the image capture system while repairs are undertaken.
FIG. 5 shows a related art system for recording and reproducing an image. This system is driven by a battery 518 having a secondary cell 514 and a battery microcomputer 515 serving to identify a valid battery. The battery microcomputer 515 derives power only from the secondary cell 514. To charge the system, a system-controlling unit 508 first communicates with the battery microcomputer 515 to determine whether the battery 518 is valid. If so, a switching circuit 513 enables a charging circuit 512 to supply power to the secondary cell 514. Otherwise, power supply to the secondary cell 514 is disabled to prevent failure.
In such related art systems, the secondary cell 514 supplies power to the battery microcomputer 515. If there is insufficient power in the secondary cell 514, the battery microcomputer 515 cannot be driven, and the user cannot successfully charge the secondary cell 514 even if the battery 518 is valid.